Wireless Joint

Have I maxed out my SINR?

My location is 22 miles from the serving tower, but at a 4000' higher elevation it's almost LOS. I can actually get signal with the 2 stock antennas on the router (Quectel EC-25AFFA modem), but the speeds are only about 4-6 mbps and not that reliable. I installed a single LPDA 10.6 db gain 700-2300 mhz antenna (w/ 25' LMR400 cable) outside, and improved the speeds to 12-17 mpbs with solid reliability. Typical signal measurements on AT&T band 14 (never congested) are:

RSRP -88 dbm
RSRQ -14 db
RSSI -57
SINR 9 db
ul bandwidth 10M
dl bandwidth 10M

I have noticed a direct correlation between SINR and DL speeds. I had planned to double up with another identical LPDA antenna for 2x MIMO but before ordering I experimented with turning the angle of the antenna I have to 45 deg in anticipation of installing another one on the same pole. The result was SINR of 4-6 with dl of 4 mpbs, no matter how finely I dialed in the direction. Given the 20+ mile distance from the tower, I wondered if a higher-gain yagi antenna in the 18dbi range might make a better first step? If the SINR can be increased to 15 or higher (highest ever w/ current config is 12) I might get DLs over 20 mbps. That would make a better starting point for going to MIMO.

What I'm wondering is whether a higher-gain antenna has the potential to increase the
SINR if the RSRP is already > -90. I've heard (I think from a Poyntang video) that increasing RSRP above -90 db doesn't increase dl speeds. OTH I've also read speculation on the forum that narrowing the beamwidth lowers the noise level, which if true would increase the SINR.

So what do you think? Are SINR and RSRQ are already maxed out for my distance from the tower since RSRP is already below -90 dbm? Or can I improve SINR with more dbi gain?

My experience with MoFi 4500 sim7 and tower 7 miles LOS with some trees locally. 2 paddles on 50' LMR400 produced about -115dBm. As I remember speeds were in the 5-10 Mbps range. Replaced paddles with MiMo panel. Signal strength went to -105dBm ±. Speeds went up to 20Mbps. Then I tried 2 cheap ($40)LP antennas from amazon. Signal strength went to -102±. Speeds sometimes up to 40Mbps. What I can say is 2 antennas do make a large jump from 1. If you can get 20Mbps with 1 antenna you should get 30 with 2 antennas. Either mimo panel or dual LP's at 90°. You will just have to try for your situation. But in no case are the small LP antennas that sharp in directivity. And I would be surprised if you can find an actual LP with a gain of over 10dB. A single wideband yagi, yes. See if you can find a 20MHz BW band, it makes a huge difference over 5 or even 10.

See if you can find a 20MHz BW band, it makes a huge difference over 5 or even 10.

I'm not maximizing 10mhz at 15 mpbs DL, so would a 20Mhz band still improve the download speeds at the same signal quality?

I would be surprised if you can find an actual LP with a gain of over 10dB. A single wideband yagi, yes.

Well there are much longer LPDAs from Poynting, Wilson, and then some China stuff on Amazon and ebay, like 4x longer (44 in.) with many more elements. The advertised dBi gains are all over the map from 11 to 18. But how could any of them not be a significant improvement over the common enclosed short LPDAs?

I know for me, there is/was a HUGE difference between channel locking on a 10MHz band that has beautiful signal strength for me and channel locking onto a 20MHz channel that really only seems to ever have two bars. the 20MHz channel with supposedly less signal stomps the crap out of the 10Mhz band. night and day difference. for me it was like 5 - 10 megs down on the 10MHz channel vs 20 - 25m down and depending on the time of day spikes up to 35m and even 50m early (pre 7 am) weekend mornings on the 20MHz channel. I do have dual Wilson external yagi wide band antennas set in MIMO configuration.

Look here https://hamwaves.com/lpda/en/index.html The optimum value for a LP antenna only gives at best 10.5dBi gain. The manufacturers values are way over inflated. Only way to determine if a wider BW channel will give you better download Mbps is to try. It's worth it.

for me it was like 5 - 10 megs down on the 10MHz channel vs 20 - 25m down and depending on the time of day spikes up to 35m and even 50m early (pre 7 am) weekend mornings on the 20MHz channel.

That sounds like congestion on the 10mhz channel, 5 to 10 down with good signal stats. I've never clocked more than 6mpbs on AT&T band 12, but regularly get 15mbps on band 14 any time of day; both are 10x channels.

As for band 2 at 20x, I haven't been able to get a good enough signal to compare. The same tower that I use for band 14 also supports band 2, but I can't lock it in for some reason; the router defaults to a different tower nowhere near my antenna direction. The LPDA antenna is supposed to be higher gain at 1900mhz (band 2) than 760 (band 14). I wonder if AT&T transmits band 2 from that tower in directions other than toward my location?

The optimum value for a LP antenna only gives at best 10.5dBi gain. The manufacturers values are way over inflated.

That web page is a little over my head; it seems that the standard enclosed LPDA is reported as 10.6 across manufactures, but the bigger LPDAs report higher gains. This got me thinking that comparisons within a single manufacture's line might clear things up, because you would think those numbers would be valid on a comparative basis. Not so much for actual dBi gain, but for the utility of different antenna types. I looked at the Wilson line and found good specs for the MHz ranges that apply. Here's the hierarchy.


The bottom 4 entries are not Wilson because they don't have these types in their line. Crossreferencing between the upper and lower sections, both Wilson & ZDA have yagis with 8 elements and identical gains. I think this validates the bigger ZDA yagis as being rated on the same scale.

A few observations:

• Manufactures usually report only one dBi value, whatever one is the maximum. It might or might not apply to your situation. The The Wireless Haven directional panel is a good example at a reported 15.0 dbi. Commendably, they offer a chart showing the gain at all bandwidths.
  
  Larger LPDAs are significantly more powerful than the standard 10.6 max LPDA, but much less so than larger narrow-band yagis.
  
  Parabolic grids are awesome over all lte bands; too bad they are so expensive and heavy. The wide-band models seem to have equally high dBi gains as the narrower-band ones. (Not shown in table.)

I know this antenna comparison is second nature to the many experts on this board. I hope this comparison helps some new to LTE like me. I'm very far from any cell towers, so I'm leaning toward the high-gain yagis for my application. 16-17 dBi is significant vs. 12-13 and they're cheaper than the large LPDAs. The downside of the yagis is you've got to choose your band; not very flexible or future-proof.